1. Field of the Invention
The present invention relates to a method and apparatus for filling containers, and more particularly, to a filling system including a fill pipe with an elliptical cross-section.
2. Description of the Related Art
Packaging machines are known that integrate the various components necessary to fill and seal a container into a single machine unit. This packaging process, generally stated, includes feeding cartons blanks into the machine, sealing the bottom of the cartons, filling the cartons with the desired contents, sealing the tops of the cartons, and then off loading the filled cartons for shipping.
Trends within the field of packaging machines point toward increasingly high capacity machines intended for rapid, continuous filling and sealing of a very large number of identical or similar packaging containers, e.g., containers of the type intended for liquid contents such as milk, juice, and the like. One such machine is disclosed in U.S. Pat. No. 5,488,812, issued Feb. 6, 1996, and entitled "Packaging Machine." The machine disclosed in the '812 patent includes a plurality of processing stations, each station implementing one or more processes to form, fill and seal the containers. Each of the processing stations is driven by one or more servomotors that drive the various components of each of the processing stations. Other such machines include the TR-6.TM. and the TR-8.TM. packaging machines available from Tetra Rex Packaging Systems, Incorporated of Buffalo Grove, Ill.
The increased throughput and decreased size requirements of packages on their packaging machines have increased the demands that are placed on the fill systems that are employed. Various apparatus and corresponding methods for filling containers, such as gable-top containers, have therefor been devised for these machines. In accordance with one of the more popular filling methods, the container is lifted from a conveyor to a fill pipe by means of a lifting mechanism. The container lifting mechanism gradually lowers the container as product is dispensed through the fill tube. The container then again engages the conveyor where it is transported to a top sealing station.
Alternatively, the filling and top sealing operations may be performed at a single location within the machine. In such instances, the container may be top sealed after it has been lowered from the fill pipe. Such a method and apparatus are shown and described in the foregoing '812 patent, and, further, in U.S. Ser. No. 08/315,414, filed Sep. 28, 1994, and entitled "Control System For A Packaging Machine."
One problem encountered when attempting to increase the speed with which a container is filled with product relates to the foaming and turbulence that occurs as a result of air and product mixing in the container. Generally stated, foaming increases as the speed with which the container is filled increases. When foaming is excessive, the product splashes into the sealing areas of the container resulting in improper sealing in subsequent sealing operation and/or contamination of the sealing area resulting in a reduction in the hygiene of the seal than would otherwise be obtained. The rate at which the container may be filled is thus limited by the foaming that occurs for a given fill rate. This problem is exacerbated with containers having a rectangular cross-section. A reduction in the velocity of the flowable material flowing through a fill pipe with a circular cross-section would lead to a reduction in the number of units produced per hour which is not a viable solution to the problem.